1. Field of the Invention
This invention relates to trim strips produced by causing metallic inserts to be extrusion coated with vinyl chloride resin, and more particularly to trim strips for use in external ornamentation of automobiles.
2. Description of the Prior Art
Generally, trim strips for external ornamentation of automobiles are required to withstand weather conditions and, because the automobiles are destined to have their shells washed with wax remover (steam containing kerosene) at the time of delivery, to resist kerosene. Most of the conventional trim strips, therefore, have been produced by causing inserts 2 such as of stainless steel to be extrusion coated with a vinyl chloride resin material (hereinafter referred to as "PVC material") capable of satisfying the requirement mentioned above (FIG. 1).
The trim strips constructed as described above, however, have posed the following problems:
(a) The adhesive property which the PVC material (particularly possessed of rigidity, Hs (Shore A), exceeding 98) exhibits to the metallic insert is not sufficient. It has been customary, therefore, to make up for the deficiency in the adhesive property by the use of a two-component polyurethane type, a PVC type, or an acrylic type adhesive agent. Despite the effort, it is not easy to produce ample adhesive strength (particularly shear strength).
(b) For the PVC material to acquire sufficient resistance to kerosene, it is required to contain its plasticizer only in a small proportion (generally not more than 30 PHR). Because of the insufficient plasticizer content, the PVC material exhibits no satisfactory extrusibility. The extruded resin coating, therefore, tends to contain therein fisheyes and fails to acquire a good outward appearance.